The Whiteboard

Matt D

00:09

heh

user55340

03:51

@Sparticus I had a -10 today too...

user55340

15:08

0

Q: Fastest way to check if two square 2D arrays are rotationally and reflectively distinct

The best idea I have so far is to rotate first array by {0, 90, 180, 270} degrees and reflect it horizontally or/and vertically. We basically get 16 variations [1] of first array and compare them with second array. if none of them matches the two arrays are rotationally and reflectively distinct....

user55340

Thats an interesting question.

Jimmy Hoffa

@MichaelT There's nothing optimal about this tail call whatsoever.

user55340

@JimmyHoffa I din't say it was optimal... just that cats are naturally familiar with tail calls and leaving the heads (of mice) around.

Jimmy Hoffa

@MichaelT Fair point

user55340

@rocking MSO rep has... dubious value. I'm fairly certain 160 rep to someone with nearly 40k rep isn't that much. And Yannis is kind of... special. some people take pity on him for the work that he does elsewhere on SE. — MichaelT 22 hours ago

user55340

15:21

(the second link has a mouseover text)

Jimmy Hoffa

@MichaelT How you do alt-text?

Jimmy Hoffa

15:38

My Haiku for the day:
I am so tired ugh
I am the code, caffeine yes
Code the tired away

@MichaelT Yeah, and the only answer there right now clearly came from someone who didn't make it to the second verse of my haiku.. Looks like the easy off-the-cuff reach for an answer always on hand "hashing, yeah.. sure" but really doesn't stand up to inspection at all

Perhaps I'll write an answer... though I do have a good bit of code that need be slung today and a design doc to write for a service that's effectively going to behave like DHCP except more complex

user55340

@JimmyHoffa [Text](link "link text")

Jimmy Hoffa

@MichaelT Hey you might have some thoughts on this

user55340

No thoughts today. Its monday.

Jimmy Hoffa

We're talking about creating an "identifier provisioning service" that will effectively just give out reusable IDs because with IIS we've got "web gardening" on which means we get multiple IIS processes, so we have our programs running multiple times on a given machine. They don't all come up at the same time either so for them to have reusable IDs when accessing things we need some way of knowing which IDs are in use already

for instance using ActiveMQ you give activeMQ a client ID when you subscribe, if your connection dies you reconnect and give it the same ClientID and it will give you all the messages you missed while you were down. But how do we give it the same ClientID without stomping on another processes ClientID? A 3rd party service that knows which IDs are in use (by keep-alive's basically) will be able to give us an available one for reuse

@MichaelT Does this make sense? What are your thoughts? You ever run into anything like this in all your back-end endeavours?

Obviously we could just use GUIDs but then we never get that reuse

so messages that go to a client won't be picked up by anybody when it comes back up etc

Ran into the same problem trying to write a Journal the other day, realized the processes will come up and try to steal eachother's Journals if they aren't told of an un-used journal they can grab by a 3rd party service

Yeah, I know, it's Monday. Chew on it, or if anyone else has thoughts, I'm going to start writing the design doc for the 3rd Party Service because it's the only way I can see of doing it (other than doing decentralized mesh ID decision making but that's more complexity than it's worth and would be a team fight because they wouldn't like the complexity)

user55340

15:56

@JimmyHoffa It does make sense... though still trying to get monday through my head.

Jimmy Hoffa

Column/Row based summation could be a quick easy heuristic to knock out a lot of your options so you only do a full equality compare when the sum of all columns/rows are identical on both sides. (Remember, the sum of columns becomes sum of rows on rotation and another rotation makes them columns again, reflection the sum stays the same) — Jimmy Hoffa 16 secs ago

@MichaelT If you come up with any thoughts or suggestions on it lemme know. It's non-trivial, so I'm happy for any ideas that simplifies it.

user55340

I was thinking "pick a corner and flood fill from there"

user55340

(for the matrix question)

Jimmy Hoffa

@MichaelT I don't know matrix math at all, I'm sure there's all types of equality techniques for them I'm unfamiliar with, but I think the heuristic I suggested is still a very good heuristic

ah yeah I think I see what you're saying

user55340

It is a very good one. I think the key decision point between the two depends on if most matrices are the same, or different.

Jimmy Hoffa

16:02

@MichaelT Yeah if there's a lot of simile my heuristic is a waste

user55340

1 2 3 --- 3 2 1
4 5 6 --- 6 5 4
7 8 9 --- 9 8 7

user55340

So you start in the upper left. You've got a 1. Then you find the 1 in the corner on the right hand matrix and find thats in the upper right. Therefore you are expecting a 2 adjacent to it (either left or bottom)... and a 4 opposite that.

Jimmy Hoffa

@MichaelT Ah yeah that makes sense

user55340

Mine catches dissimilar faster (I think) than the row / col sum. But when they are mostly the same matrixes being compared, I think mine would end up doing more work than yours.

Jimmy Hoffa

True because yours has the possibility of knocking out all possibilities before one iteration, mines requires one full iteration no matter what

user55340

16:05

Because its all about doing comparisons - item by item. Yours is rather 'blunt' - just sum them all up, and then compare the sums. If they are the same, you've only done a few comparisons (of the sums)

Jimmy Hoffa

It's kind of a strange question if you think about it because you're trying to optimize past O(n) of the striaght equality check, and in reality you would basically never optimize past O(n)

In an embedded scenario you may optimize for space but even in embedded O(n) is generally totally acceptable

Well I'm off to sling some code... get some crap wrapped up so I can start designing that service..

user55340

16:26

@JimmyHoffa Its not just a straight equality check. You've also got the "determine the rotation or flip" that foils the simple equality check.

Jimmy Hoffa

@MichaelT Doesn't foil it, just makes it O(4n) or however many variations you have

Further it is parallelizable

user55340

@JimmyHoffa 16 possible rotations and flips.

Jimmy Hoffa

@MichaelT Nonsense, some portion of those are redundant

user55340

It is certainly trivially parallelizable.

Jimmy Hoffa

It would be pretty simple in fact to do multiple checks in a single iteration

if not all of them

user55340

16:32

@JimmyHoffa Its still monday (I typo'ed that and it became monad)... so still not sure.

Jimmy Hoffa

it's just a matter of having pointers to your comparison points and moving them in the correct direction

pointer to top left and mid-left, compare them, step each forward to the right one, compare, with each step forward you are checking for top-bottom reflectivity. Have 2 other pointers for left-right reflectivity, and two others for 90 degree rotation, etc

Have a function for moving each pointer forward Tuple<Point,Point> MoveLeftRightPointers(Point leftPoint, Point rightPoint)

get your 16 functions, each iteration you let the functions move your points, do your comparison and cull comparisons with bools _leftRightNotReflective = true;

you should rationally be able to do all comparisons in a single iteration like that

fuck would that be a mess though heh

But so it is with optimized code

and now you have O(1n) worst case, and who bloody tries to optimize past that

user55340

I'd start with a data structure that represents the 16 hypothesis that assume that the two are equal, find an equal corner, and then start eliminating them by doing the appropriate comparisons.

user55340

But again, the direction of optimization that needs to be taken depends upon if the original belief is that they are the same matrix, or different matrixes. This works on the assumption that they are different ones and tries to find the inconsistencies as fast as possible... but if they are the same, it may be less than optimal.

Jimmy Hoffa

O shit, mentioning data structures something just came to me, I could be way off but for inspecting dimensional spaces quad-trees are supposed to be great.

I wonder if there's a way to play off that. Though I know they're mainly useful for seeing collissions

user55340

17:00

@gnat FWIW, the cliff questions v2 against StackOverflow - I've tweaked it so that it has a date range in there. Runs very fast now for a 1 month range.

user55340

17:19

In my scenario I have boolean arrays and I am only comparing ones with same number of true/false elements, so checksums won't improve anything. But generally it's a good idea. — kustrle 26 mins ago

Jimmy Hoffa

@MichaelT ..why wouldn't it improve anything? You can sum true/false

user55340

This changes many things. For example, my 'find the matching corner' approach is assuming integers.

Jimmy Hoffa

You'd have a lot more collissions but still

user55340

@JimmyHoffa It would have many more collisions... yea.

Jimmy Hoffa

@MichaelT Though it depends on the size, think about this: a true/false array of 32 members is effectively an integer. The summation has a possibility up to 4 billion

There's a large enough range then to avoid collissions quite well

at 8 you have a range up to 255 though

then you're kind of stinkered

user55340

17:21

The thing is, you'd have lots more false positives that it would really only be useful if the value was likely different.

user55340

Lets look at a 1x4 that's been flipped...

Jimmy Hoffa

@MichaelT Ehh iduno, further think about the column count, 8 x 4 columns again up to 4 billion varieties

user55340

But how do you determine if its been flipped or not? The values aren't trivially the same.

Jimmy Hoffa

hey @MichaelT do me a favor, point at your head. Are you pointing? Now abbreviate mountain. Happy Monday.

user55340

@JimmyHoffa Yea... I said my initials... thats me. So? ;-)

user55340

17:25

(and yes, I am kind out of it... beyond it being a monday.)

Jimmy Hoffa

..she tied you to a kitchen chair, she broke your throne and she cut your hair.. Leonard Cohen's pretty cool.

@MichaelT Enjoy a bit of the grappa last night?

user55340

Nope... I'm blaming the changing humidity, lack of hydration (dehydrate faster when its dry), and a tad bit on lack of sleep.

Jimmy Hoffa

@MichaelT That's pretty thin, you may as well throw in solar flares at that point

user55340

@JimmyHoffa I've got a number of variations of that song.

Jimmy Hoffa

Much as I am anti-religious, I can't help but love that song just because it's a song vocalists can do so many awesome things with

user55340

17:28

It draws from religious imagery, though I don't see it as a religious song.

user55340

I see it more as a song about love and the betrayals associated with it.

user55340

> Maybe there’s a God above
But all I’ve ever learned from love
Was how to shoot at someone who outdrew you
It’s not a cry you can hear at night
It’s not somebody who has seen the light
It’s a cold and it’s a broken Hallelujah

user55340

In some versions the counterpoint between the music (celebratory vs wording) is interesting to listen to.

Jimmy Hoffa

Yeah that's the first time I ever noticed the words were changed the "she tied you to a kitchen chair" just caught my ears and I'm like "wait wait, that can't be the original wording.."

user55340

@JimmyHoffa Alluding to Sampson... but yep.

Jimmy Hoffa

17:34

@MichaelT ?

user55340

Samson

Samson (, meaning "man of the sun"); Shamshoun ( /) or Sampson () is one of the last of the Judges of the ancient Israelites mentioned in the Hebrew Bible (Book of Judges chapters 13 to 16). According to the biblical account, Samson was given supernatural strength by God in order to combat his enemies and perform heroic feats such as killing a lion, slaying an entire army with only the jawbone of an ass, and destroying a pagan temple. Samson had two vulnerabilities, however: his attraction to untrustworthy women and his hair, without which he was powerless. These vulnerabilities ultim...

user55340

> Samson had two vulnerabilities, however: his attraction to untrustworthy women and his hair, without which he was powerless. These vulnerabilities ultimately proved fatal for him.

Jimmy Hoffa

Ah interesting

I had a feeling it was likely related to something religious, but either way it just sounds badass

user55340

The bathing from the roof is from King David...

user55340

> The story of David's seduction of Bathsheba, told in 2 Samuel 11, is omitted in Chronicles. The story is told that David, while walking on the roof of his palace, saw Bathsheba, who was then the wife of Uriah, having a bath. He immediately desired her and later made her pregnant.

Jimmy Hoffa

17:37

@MichaelT Heh thanks, my monitors stare straight out into the open space of the office

user55340

@JimmyHoffa Yea... didn't really need that sticking out during work hours.

Jimmy Hoffa

Speaking of fun lyrics, this has to be my favorite of recent:

►

The lyrics tell a whole horror story basically

@MichaelT Such great G-rated wording "made her pregnant" like he waved his hands and said some incantations or something

"I desired her, so I said Baby Sesame! and she was pregnant!"

user55340

Lets see... Hallelujah by Jeff Buckley, John Cale (x2 - once from I'm your Fan, once from Music from Scrubs), Rufus Wainwright (Shrek), The Rubes (Carnival Girls).

Jimmy Hoffa

@MichaelT Which lyric does Leonard Cohen sing I wonder?

user55340

@JimmyHoffa Hmm? Which which lyric?

Jimmy Hoffa

17:42

@MichaelT azlyrics.com/lyrics/leonardcohen/hallelujah.html

> Your faith was strong but you needed proof
> You saw her bathing on the roof
> Her beauty in the moonlight overthrew you
> She tied you to a kitchen chair
> She broke your throne, and she cut your hair
> And from your lips she drew the Hallelujah

user55340

Thats the version Cohen sings. I've heard some that skip a verse or switch them around...

user55340

►

user55340

That's probably the best known other version.

Jimmy Hoffa

@MichaelT Right, is that Cohen's own lyrics or is that written by one of the variation writers you listed above?

user55340

►

user55340

17:44

There's the cohen version.

Jimmy Hoffa

@MichaelT I was just listening to it, I know his version I meant who wrote it

I'm calling it now, you got a cold. Otherwise solar flares are at play because you are not with it this morning heh

user55340

Nope... I'm really not with it... not a cold though. Just feel like my head is a bit detached.

Jimmy Hoffa

Whenever I get a cold the early warning sign is always an extreme tiredness with no real reasonable cause, usually happens at least one to two days before any other symptoms

user55340

I'm sticking with the hydration theory... and I'm working on that (drinking a bit - lemon aid... not other types of drinking).

user55340

Quite possible, co-worker out sick today.

Jimmy Hoffa

17:48

@MichaelT Emergen-C

I'm getting over something myself. Took 2 damned weeks, is this what getting older is? Colds lasting 2 fucking weeks? That was horrible. Now I'm just clearing it out of my chest but not still sick.

user55340

@JimmyHoffa I should get another big bag of Halls defense.

Jimmy Hoffa

On the other hand I wonder if cold viruses are getting stronger with medical trends and such that only the strongest ones survive now

user55340

Its not so much "the strongest survive" but rather the rapid mutation of the virus... and yea, we are getting older.

user55340

My niece (4) catches a cold... she's got it for a day and the next day she's good. My father catches the same cold from her, and he's not at 100% for a week.

Jimmy Hoffa

@MichaelT yeah, same thing happened to me last year, got a cold and it just knocked me out for 2 solid weeks. Time was a cold only kept me down for ~2-3 days

Yeah well one thing's for damn sure: Children will get you sick as hell. I never had so many colds as when my kid started going to daycare heh, they're little mobile germ-bags

user55340

17:53

(niece (4) and nephew (2) had a fight last night... building blocks (big ones). He wanted to make a rocket ship, she wanted to make a castle... not sure who won - its one that you just have to let them sort out for themselves... though this morning, my mother sent a picture of my nephew in a "rocket ship" with a space helmet (strainer))

Jimmy Hoffa

haha nice

user55340

Ohh! Tim Post posted on our Meta (always fun to see what SE employees show up there)

user55340

You get glimpses into the collective mind of SE about directions the network is taking.

user55340

0

A: Bringing topics together in the stack exchange

The Scala tag wiki on Stack Overflow is rather, well, interesting in this regard - have a look at it. Someone actually wove together almost an entire language tutorial from one question successively to another, then another. That's great for a whole language tag, but it doesn't really allow for t...

Jimmy Hoffa

@MichaelT I gotta say, it seems like SE is on auto-pilot. I don't think it's really taking directions so much as maintaining the quality it's got; "Happily ever after."

They tweak and twiddle sure, but I see no actual shift of any sort anywhere or serious change for that matter

user55340

17:59

@JimmyHoffa I wouldn't say autopilot... more "there is a lot of inertia and we have to make very gradual changes to it - we don't want another 90 deg turn like NPR/P.SE to disrupt things"

user55340

The close reasons were a significant adjustment to how things work.

Jimmy Hoffa

If they wanted to do something truly crazy and interesting, they would start a new SE and try and make a social site of it; make private messaging available, create git capabilities, and see what projects naturally grow from the collaboration of people active in the SE community

keeping the Q&A at the heart of it, it would be curious to see what might grow up naturally from that group

user55340

The danger there is cannablizing something that they already have and works.

Jimmy Hoffa

of course

just saying, they're not going to do anything new or interesting

What we have is what we get

There's plenty of interesting things they could do, but they won't do any of them. Auto-pilot.

(not that it's a bad thing, if SE were destroyed through accident or misguidance the internet would be a much sadder place)

user55340

-5

A: How do I dissuade users from using the same password with similar systems?

It is simple, you can define your own password validation which is not commonly used by other websites like Minimum 2 uppercase letters. Minimum 3 symbols. Minimum 2 numbers and min 2 lowercase letters. User may feel uncomfortable on creating passwords, but i am sure that those will be unique.

user55340

18:08

Ahh, but I already use P4$$W0rd. for Gmail. Ha! Foiled you! — MichaelT 20 secs ago

Jimmy Hoffa

18:20

@MichaelT Require that the name of the system is somewhere in the password for that system on each system :D

user55340

I recall the entry in the evil VMS admin book. Require that the password be between 64 and 64 characters long, be the system generated vaguely pronounceable line noise, require 8 successful repetitions (in a row) of the password to accept the new one, expires after 1 use... and a second password that has all the same parameters.

user55340

So, you log in... "your password has expired. Your new password is {64 character long string}. Please type it to verify you have it. (x8). You have a second password, it is {64 character long string}...." each time you log in.

Jimmy Hoffa

@MichaelT haha that is spectacular.

user55340

Seriously... don't piss off VMS admins. Now days, they'll get out their walkers and beat you with some JCL manuals from the Grey Wall.

user55340

Jimmy Hoffa

18:28

haha yeah, that's a case of "The old school is scary"

user55340

> Big Gray Wall

n. What faces a VMS user searching for documentation. A full VMS kit comes on a pallet, the documentation taking up around 15 feet of shelf space before the addition of layered products such as compilers, databases, multivendor networking, and programming tools. Recent (since VMS version 5) documentation comes with gray binders; under VMS version 4 the binders were orange (`big orange wall'), and under version 3 they were blue. See VMS. Often contracted to `Gray Wall'.

user55340

18:53

Hmm... not as fond of that arrangement by The Del McCoury Band of 1952 Vincent Black Lightning.

user55340

I prefer the Richard Thompson arrangement... lets see if I can find them...

user55340

►

user55340

►

user55340

(listening to a streaming radio station)

Jimmy Hoffa

...and there's a creepy doll, that always follows you, it's got a ruined eye, that's always open. And there's a creepy doll, that always follows you, it's got a pretty mouth, to swallow, you whole.

@MichaelT What station?

user55340

19:02

itunes radio.

Jimmy Hoffa

ah

user55340

Built from Sam Bush, Shawn Mullins, Marc Cohn, Eric Clapton, and Bruce Hornsby.

Jimmy Hoffa

Yeah, Iduno most of those.

Something worth looking into I suppose

though it's hard to stop listening to Jonathan Coulton when I start, he's too hilarious.

Jeremy Dicaire

Hi guya

user55340

last.fm/user/turnmichael to see what I've been listening to.

Jeremy Dicaire

19:05

It's quite silent here

user55340

Its monday... and my mind feels a bit detached.

Jeremy Dicaire

Hahaha well said

I just lost all my photos :(

user55340

? how 'lost'?

user55340

Btw, wow - have you looked at the scala tag on SO? stackoverflow.com/tags/scala/info

Jimmy Hoffa

@MichaelT I've seen some stuff like that around tags

but yeah wow

user55340

19:19

@JimmyHoffa Note that the scala tag on SO likely has as many users watching it (answering, deleting, closing) as all of P.SE.

Jimmy Hoffa

True

user55340

And I doubt we have anything as... cohesive of an idea as a language tag on SO.

Jimmy Hoffa

Just looking through language tags, you could really learn a lot just by going through all the SO language tags and reading the wisdom within, each language tag presumably written by language lawyers for that language

user55340

Absolutely.

user55340

Our biggest tag is java with 1970 questions. Scala has 20k questions on SO. P.SE has 28k questions total.

Jimmy Hoffa

19:25

@MichaelT and 18k of them are closed garbage

@MichaelT C++ has 240k questions on so, 540k for C#

512k for java

user41796

@JimmyHoffa - is that a hint more things need to get deleted around here?

user55340

data.stackexchange.com/programmers/query/141090/…

Jimmy Hoffa

@GlenH7 Did you think less things need to get deleted around here?

user41796

@JimmyHoffa Well, yes because things are being deleted. Ergo there's less that needs to be deleted.

user41796

And holy carp! I just looked at the scala tag wiki over on SO

user55340

19:30

@GlenH7 Yea... I know.

user55340

(might want to tweak that tag link to the actual SO link)

user41796

@MichaelT That would require effort to copy & paste the URL.

user41796

:-)

user41796

And the comment just aged out... I know, I'll just flag it for moderator attention instead.

user55340

[scala tag on SO](http://stackoverflow.com/tags/scala/info)

user55340

19:33

Wanna try again? We can depin and clean the stars...

user41796

I'll let you have the fame instead. If it's from you, people will know it's mind blowing. From me, they'll just assume more snark. :-)

Jimmy Hoffa

> you gotta make the money first. Then when you get the money, you get the power. Then when you get the power, then you get the women.

user55340

> And holy carp! I just looked at the scala tag wiki over on SO --GlenH7

Jimmy Hoffa

user55340

@JimmyHoffa Have you seen how much fecal mater they put out? I'm sure they produce it fresh too.

user41796

19:38

@JimmyHoffa They are bottom feeders, right?

user41796

Some of my screens are turning pink. Such a pretty color.

user55340

@GlenH7 Go glance at programmers.stackexchange.com/questions/10675/…

user55340

Look at how many deleted answers are in that one.

user41796

@MichaelT Wow, our resident evil mod really went on a rampage with that one.

Jimmy Hoffa

@GlenH7 Left your speakers too close to your CRT? I hate when that happens.

user55340

19:46

@JimmyHoffa He's catching up on questions with 2 delete votes looking for a third.

user41796

And I really think there ought to be on-screen fireworks when casting the deciding delete vote.

user41796

Bigger, splashier ones than what should be in place for the 5th close vote.

user55340

Turning pink isn't enough? Though, given the color, you might be able to ask MSO to make unicorns run across the screen when that happens.

Jimmy Hoffa

@GlenH7 I just want fireworks arbitrarily and randomly. There should be a chrome plugin for this: Every random number of clicks around chrome you get fireworks, just empty gratification for browsing the web. As if there's not already enough of that.

user41796

I need to learn javascript in the coming months. Maybe I'll find a slick presentation framework and write my own SE plugin to make the fireworks appear.

user55340

19:51

@GlenH7 Write a greasemonkey script or chrome plugin?

Jimmy Hoffa

@GlenH7 Just read crockford, it's surprisingly small

@GlenH7 amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/…

It's genuinely tiny

user41796

@MichaelT Not sure yet. TBD...

user41796

@JimmyHoffa He's a pretty cool and low-key guy. Listened to a keynote session he gave along with a panel on web development.

user41796

When I start learning JS, my goal is to run everything against JSLint and get "trained" the right way. Hopefully I won't cry too much.

Jimmy Hoffa

@GlenH7 Yeah, what do you expect, he's one of those genius sorts; degree in radio broadcasting turned lisper turned yahoo's javascript genius

@GlenH7 JSLint is his work (originally)

jozefg

19:53

@JimmyHoffa But he still sucks at explaining monads.

Jimmy Hoffa

Really though, get the book. It's really small and a very easy read because he's a good personable writer like that

@jozefg haha I know, I saw that, iduno it wasn't terrible but I pretty well disagree with some of his statements in there

user41796

@JimmyHoffa He also can lay claim to "discovering" JSON. He doesn't like the term "invented" for that particular technology

Jimmy Hoffa

I'm just glad he started it with the truth that as soon as you understand them, you immediately lose all ability to explain them to others

user41796

@jozefg His session was on programming language syntax. And it was a struggle to get through some parts of it. His presentation skills could use some work, no doubt.

Jimmy Hoffa

but I wish he didn't tell people "Yeah you can learn these in any language sure why not?"

jozefg

19:55

@JimmyHoffa Yeah, dynamically typed monads lose some of the simplicity actually

Types Are Good (Ignorance is Strength)

Jimmy Hoffa

All of this "You can learn FP stuff in any language with some minor FP constructs" is like telling people "You can learn to scuba dive in a kiddy pool, all you need is enough depth to put your head under the water". Though theoretically true, it just won't work out that way.

user41796

(I need more delete votes)

Jimmy Hoffa

Every so many people who try to scuba dive just freak out. Completely lose their shit. Dunno why, saw it happen twice in my trips, first timer did everything fine then they get out and as soon as they start going down 10-15-20-25 feet they just lose their shit and start swimming up

One of those things you can't know what'll happen until you do it

user41796

@JimmyHoffa Happened to my wife. She won't go again, afaik. I freaked on my first dive, but managed to get it back under control. I only went on one trip, but I'd happily go again.

Jimmy Hoffa

Has to be scary as hell for the divemaster taking them down heh, freaked me out seeing someone do that with how much you're trained explicitly how dangerous that is

user41796

20:00

For me, it was the combination of being completely surrounded by the water but becoming cognizant of being in a massively open space. The two feelings just slammed against each other.

user55340

I'm not about to go diving... just curious though, how long were they down at depth?

Jimmy Hoffa

@MichaelT It's the sinking that does it

user41796

That's my observation as well - the freak out happens the moment you hit the water

user55340

If you went down to 25 quickly and then straight back up, would the nitrogen narcosis have time to get into effect (and the related issues)?

Jimmy Hoffa

I think it's part of the combination of seeing the open-air drift away further over their head causes like a claustrophobic reaction

@MichaelT It's not the narcosis, it's the bends, narcosis happens at much higher depths and when you're down for too long as nitrogen builds up in your system

user41796

20:02

Or perhaps the transition from having fixed boundaries (on the boat) and then those boundaries disappearing after you drop in.

Jimmy Hoffa

The bends are you go down, take a breath, hold it going up and the oxygen in your bloodstream expands into bubbles which cause clots

or other general problems of having oxygen bubbles in your blood

user55340

Ok, wrong term... yep, the bends... and would it be an issue if you went straight down and back up?

user55340

Or is it that it needs to have some time to come out of solution?

Jimmy Hoffa

@MichaelT You can get the bends taking a breath at 5 feet down

I don't know how long it takes, it's a matter of getting enough oxygen into your blood stream at that depth, and going up too quickly without breathing out to release the oxygen

user55340

> Except for helium and probably neon, all gases that can be breathed have a narcotic effect, although widely varying in degree.

Jimmy Hoffa

20:04

it's just one of those "don't even effing try it" type of things you're trained during the classes that it's ridiculously dangerous and how much it takes doesn't matter

user41796

@JimmyHoffa it's the pressure differential, IIRC, that triggers the bends

Jimmy Hoffa

@MichaelT argon too?

I thought argon was explicitly inert

user55340

> The noble gases argon, krypton, and xenon are more narcotic than nitrogen at a given pressure, and xenon has so much anesthetic activity that it is a usable anesthetic at 80% concentration and normal atmospheric pressure. Xenon has historically been too expensive to be used very much in practice, but it has been successfully used for surgical operations, and xenon anesthesia systems are still being proposed and designed.

Jimmy Hoffa

@MichaelT interesting

user55340

Nitrogen narcosis

Narcosis while diving (also known as nitrogen narcosis, inert gas narcosis, raptures of the deep, Martini effect), is a reversible alteration in consciousness that occurs while diving at depth. It is caused by the anesthetic effect of certain gases at high pressure. The Greek word ναρκωσις (narcosis) is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates. Narcosis produces a state similar to drunkenness (alcohol intoxication), or nitrous oxide inhalation. It can occur during shallow dives, but does not usually become noti...

Jimmy Hoffa

20:05

@GlenH7 Yeah, that's why it only takes a few feet

user55340

Theories of general anaesthetic action

A general anaesthetic (or anesthetic) is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthetist/anaesthesiologist in order to induce or maintain general anaesthesia to facilitate surgery. General anaesthetics have been widely used in surgery since 1842 when Crawford Long for the first time administered diethyl ether to a patient and performed a painless operation. It has always been believed that general anaesthetics exert their effects (analgesia, amnesia, immobility) by modulating the activity of membrane proteins in the ne...

user55340

And then...

user55340

Jimmy Hoffa

The weight of water causes such significant pressure as to take very little to cause a significant differential on the oxygen. It's interesting how different depths you use different gasses based on the size of their molecules

Molecular size effects their compression/expansion with pressure

user55340

Hydrogen narcosis can be experienced at 300 meters...

user55340

20:08

(though its a "detectable" not a "problem")

Jimmy Hoffa

Yeah most of the narcosis is based on oxygen deprivation I suppose, though there's some smarmy claims out there about different pressures causes the nitrogen + oxygen combination to be in the right circumstances making N2O laughing gas, but I don't know enough about chemistry/physics to know any truth to that

What you're saying about other inert gases makes me think even if it is true it has basically nothing to do with the effect

user41796

@JimmyHoffa presuming you have the right molecules in place, any chemical reaction can take place. It's the external factors like temperature and pressure that dictate the stoichiometry of the equation.

Jimmy Hoffa

@GlenH7 You clearly made that word up. I'll hear no more of it.

user55340

Stoichiometry

Stoichiometry is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of positive integers. For example, in a reaction that forms ammonia (NH3), exactly one molecule of nitrogen gas (N2) reacts with three molecules of hydrogen gas (H2) to produce two molecules of NH3: : + 3 → 2 This particular kind of stoichiometry - describing the quantitative relationships among substances as they participate in chemical reacti...

user41796

@JimmyHoffa Had to double check the spelling on dictionary.com

user41796

20:14

2 N2 + 02 <=> 2 N2O. And that would definitely be double arrows on that equation

Jimmy Hoffa

One pain in the ass for me is being native to Denver, whenever I do go diving I run the tank down before anyone else in the group because my lungs pull in more than people from normal altitudes

and I'm a small fella so I always get crap for it heh

user41796

@JimmyHoffa one of my brothers has a similar complaint as yours. Doesn't stop him from enjoying the dive though.

Jimmy Hoffa

@GlenH7 Yeah, I love it, nobody complains too much because everyone's in a good mood on a dive

user55340

@GlenH7 @gnat fun simple search to hit - programmers.stackexchange.com/… --- closed questions with no answers that are not a dup and not migrated.

user41796

@MichaelT Soon I'll be out of votes for the day too!

user55340

20:31

I'm still wondering how this got +7/-2 ...

user55340

5

Q: What are the most important things for Java developers to learn when learning iOS programming

I imagine there are now quite a few Java programmers in the world who have taught themselves Objective C and iOS programming. Shifting technology stacks like this always results in a lot of "Aha!" moments as crucial ideas and differences are learned and unhelpful patterns from the old technolog...

java ios learning-curve

user55340

That was posted Sep 3rd. Two months ago.

user55340

I'm gonna blame the students.

user41796

@MichaelT Popular subjects. Up votes == "I'm interested in this too!!!"

user41796

And clearly the students failed to read your letter....

user55340

20:35

They had a fun bit that showed up on MSO earlier today... a first post audit on SO that the guy failed because it was a 0 rep answer that was deleted as part of the homework asker deleting the question (to hide that he asked on SO?) - he said no action needed and it was thought to be a bad one (because it was deleted).

user41796

the audit selection algorithm could use some improvement. But I will ashamedly note that I wasn't able to roll through the various questions that were presented as samples in Shog9's MSO question a month back. Simply had too much going on at the time.

user55340

Nor I.

user55340

Half trying to think of if its worth it to make a sparse matrix where x,y are non-ordinal types (i.e.: strings).

user55340

That said, I doubt there will ever be two items in one of the dimensions... though its nonetheless maybe interesting.

user55340

The alternative is to just use a simple HashMap with concatenated strings... but thats kind of boring and I don't really enjoy the constant smashing of strings to gather to get the keys.

user41796

20:41

@MichaelT The advanced version of gold-plating. I say go for it.

user55340

Part of it is that I'm a bit disconnected from reality today... either a cold coming on or the shift in seasons getting to me... and I have trouble thinking through the actual item I"m supposed to be thinking about.

user55340

(and the guy I need to ask questions of is also out sick)

user41796

gold plating it is!!

user55340

I'll do the working one with String smashing... gold plate a bit more later.

user41796

The problem with that is you'll end up writing some brilliant code, and when you come back to it later you'll have no idea how you pulled it together.

user55340

20:44

I'm half worried about that too... though I'm not sure how brilliant I am at this point.

jozefg

@MichaelT A simple solution to that might be to create some form of time machine and then your future self can simply ask present day you for information. I'd recommend starting by looking at the Tardis monad. hackage.haskell.org/package/tardis-0.3.0.0/docs/…

user41796

@jozefg That's a pin just for the Tardis reference within Haskell.

jozefg

@GlenH7 I love that package :D

user55340

@jozefg See, the problem with that is if I had a time machine, I'd go back to when the company that I worked for had a stock price of $150 and tell myself to sell all... and then I wouldn't need to work today, and well... I wouldn't have the information for the other future self seeking the information.

2

user55340

Jimmy Hoffa

20:49

@MichaelT If I had a time machine I'd probably get trampled by dinosaurs, but it would be so worth it.

jozefg

@MichaelT Than you could just hire someone to figure it out for you

Though I feel a paradox lurking in there

user55340

(ballpark estimate if I had sold all at that peak is $7.2M before taxes... I ended up with much less than that selling not all then and more later... though I'm not complaining... my numbers are all in the black. I know people who were playing with margins back then and ended up way in the red)

jozefg

21:09

@JimmyHoffa I'm designing a funny functional scripting language

Jimmy Hoffa

21:32

lol x y z = x z ( y z )
rofl x y = x
HAH x = x

Funny Functional Scripting Language, turing complete :)

@jozefg You'll have to link me the bucket or what not when you get something working

jozefg

@JimmyHoffa I shall! Also, you can get rid of HAH since lol rofl rofl x = x

Jimmy Hoffa

@jozefg I know, but HAH makes it funnier :D

user55340

22:12

@ChrisF Just want to let you know "thank you - I do appreciate your janitorial work on that question"

ChrisF

No problem. There were some good answers there. If I've missed any let me know

user55340

@ChrisF Looks like you've gotten the good ones there. One might make the case for programmers.stackexchange.com/a/68490/40980 - I'm not completely trusting my judgement today.

ChrisF

I was using a score of at least 10 as the obvious cut off, but there were a couple of higher scoring ones that I decided weren't good enough. This one probably is though.

user55340

Indeed - some of the >10 were essentially "You should try Go" and similar answers.

user55340

@ChrisF the way I found it was I was poking at programmers.stackexchange.com/… - closed questions with no answers (that aren't dups and haven't been migrated). They are of... questionable value as they aren't serving as sign posts for dups, and aren't serving as answers for people to find... And some of them are failed migrations that should either be "yea, it was a different time then" or "nope, this needs to go"

ChrisF

22:26

@MichaelT Good catch. Keep flagging

user55340

22:39

Gah! I saw it! I can't unsee it now! The desktop photo with the milky way on the mac has coma aberration.

user55340

(for a bit about it, and a really nice camera lens... imaging.nikon.com/history/nikkor/16 )

user55340

Bit from the upper right of the image. See how all of them have little 'tails' - thats the aberration.

user55340

(diffraction spikes don't bug me... coma aberration though... I had a cheap wide lens that I took some really nice night photos of San Francisco. I then looked at them critically and every single window was a little triangle pointing at the center of the image.)

user55340

user20683

23:11

Fibonacci as written by various groups

Jimmy Hoffa

23:24

@WorldEngineer Suddenly I'm given to the inclination that a hackathon is not some place to find anyone who knows what they're doing

user20683

@JimmyHoffa yeah

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